Grant: Project Grant

People with spinal cord injury (SCI) often develop excessive and unwanted involuntary contractions (spasticity) that can produce pain, hamper sleep and impair residual motor function, with most treatments producing unwanted side effects like persistent drowsiness and muscle weakness. Recently, we have discovered that applying transcutaneous electrical nerve stimulation, or TENS, over the lower back can dramatically reduces spasticity and improves control of spared voluntary leg activation. In this project, we are examining if TENS works by changing how the motoneurons in the spinal cord respond to inputs from the brain and body. Motoneurons are the final communication relay from the brain and spinal cord to the muscles of the limbs and they contain several ion channels that make them respond in a complicated way to the inputs they receive. These complexities are coped with normally to produce smooth muscle contractions, but with SCI, they produce new challenges to regain skilled motor function in addition to producing spasticity. In this project, we examine how the currents that flow through these ion channels affect motoneuron activation normally, how they evolve as spasticity develops after injury and how they can be modified with TENS to reduce spasticity and improve motor recovery. Parallel experiments will be done in animals and humans along with computer models of the motor neuron to verify the biological results. The findings from this project will provide important information as to how motoneurons are impacted after SCI and how TENS applied to the lower back modifies the response of the motoneurons to reduce troublesome spasticity and improve residual motor function. TENS has the potential to provide an on-demand control of spasticity that is specific to the lower limb and overcomes the unwanted side effects of sedation and muscle weakness of current anti-spastic drugs, providing a promising, accessible, and safe therapy for people with SCI.